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The task of a first principles theoretical calculation of the rate of gas–liquid nucleation has remained largely incomplete despite the existence of reliable results from unbiased simulation studies at large supersaturation. Although the classical nucleation theory formulated by Becker–Doring–Zeldovich about a century ago provides an elegant, widely used picture of nucleation in a first-order phase transition, the theory finds difficulties in predicting the rate accurately, especially in the case of gas-to-liquid nucleation. Here, we use a multiple-order parameter description to construct the nucleation free energy surface needed to calculate the nucleation rate. A multidimensional non-Markovian (MDNM) rate theory formulation that generalizes Langer's well-known nucleation theory by using the Grote–Hynes MDNM treatment is used to obtain the rate of barrier crossing. We find good agreement of the theory with the rate obtained by direct unbiased molecular dynamics simulations—the latter is feasible at large supersaturation, S. The theory gives an experimentally strong dependence of the rate of nucleation on supersaturation, S. Interestingly, we find a strong influence of the frequency-dependent friction coefficient at the barrier top. This arises from multiple recrossings of the barrier surface. We find that a Markovian theory, such as Langer's formulation, fails to capture the rate quantitatively. In addition, the multidimensional transition state theory expression performs poorly, revealing the underlying role of the friction coefficient. [ABSTRACT FROM AUTHOR]

Nanoconfined poly(4-methylstyrene) [P(4-MS)] films exhibit reductions in glass transition temperature (Tg) relative to bulk Tg (Tg,bulk). Ellipsometry reveals that 15-nm-thick P(4-MS) films supported on silicon exhibit Tg − Tg,bulk = − 15 °C. P(4-MS) films also exhibit fragility-confinement effects; fragility decreases ∼60% in going from bulk to a 20-nm-thick film. Previous research found that incorporating 2–6 mol % 2-ethylhexyl acrylate (EHA) comonomer in styrene-based random copolymers eliminates Tg- and fragility-confinement effects in polystyrene. Here, we demonstrate that incorporating 3 mol % EHA in a 4-MS-based random copolymer, 97/3 P(4-MS/EHA), eliminates the Tg- and fragility-confinement effects. The invariance of fragility with nanoconfinement of 97/3 P(4-MS/EHA) films, hypothesized to originate from the interdigitation of ethylhexyl groups, indicates that the presence of EHA prevents the free surface from perturbing chain packing and the cooperative mobility associated with Tg. This method of eliminating confinement effects is advantageous as it relies on the simplest of polymerization methods and neat copolymer only slightly altered in composition from homopolymer. We also investigated whether we could eliminate the Tg-confinement effect with low levels of 2-ethylhexyl methacrylate (EHMA) in 4-MS-based or styrene-based copolymers. Although EHMA is structurally nearly identical to EHA, 4-MS-based and styrene-based copolymers incorporating 4 mol % EHMA exhibit Tg-confinement effects similar to P(4-MS) and polystyrene. These results support the special character of EHA in eliminating confinement effects originating at free surfaces. [ABSTRACT FROM AUTHOR]

Many methods to accelerate sampling of molecular configurations are based on the idea that temperature can be used to accelerate rare transitions. These methods typically compute equilibrium properties at a target temperature using reweighting or through Monte Carlo exchanges between replicas at higher temperatures. A recent paper [G. M. Rotskoff and E. Vanden-Eijnden, Phys. Rev. Lett. 122, 150602 (2019)] demonstrated that accurate equilibrium densities of states can also be computed through a nonequilibrium "quench" process, where sampling is performed at a higher temperature to encourage rapid mixing and then quenched to lower energy states with dissipative dynamics. Here, we provide an implementation of the quench dynamics in LAMMPS and evaluate a new formulation of nonequilibrium estimators for the computation of partition functions or free energy surfaces (FESs) of molecular systems. We show that the method is exact for a minimal model of N-independent harmonic springs and use these analytical results to develop heuristics for the amount of quenching required to obtain accurate sampling. We then test the quench approach on alanine dipeptide, where we show that it gives an FES that is accurate near the most stable configurations using the quench approach but disagrees with a reference umbrella sampling calculation in high FE regions. We then show that combining quenching with umbrella sampling allows the efficient calculation of the free energy in all regions. Moreover, by using this combined scheme, we obtain the FES across a range of temperatures at no additional cost, making it much more efficient than standard umbrella sampling if this information is required. Finally, we discuss how this approach can be extended to solute tempering and demonstrate that it is highly accurate for the case of solvated alanine dipeptide without any additional modifications. [ABSTRACT FROM AUTHOR]

The fragility of glass describes how rapidly its molecules slow down as it is cooled near its glass transition temperature. In nanoscale films, polymer glasses with higher fragility experience larger reductions in their Tg compared to those with lower fragility. We investigated whether this is due to the free surface of the polymers, which can cause the surface Tg (Tgsurf) to decrease relative to the bulk Tg. By measuring Tgsurf of various polymers, we found that the shift in Tgsurf relative to the bulk Tg increased with fragility. This suggests that more fragile polymers are more susceptible to the free surface effect. We explain this using the concept of energy landscape, as it is used to explain the different slowdown rates between strong and fragile glass formers at Tg. [ABSTRACT FROM AUTHOR]

How to fabricate perpendicularly oriented domains (PODs) of lamellar and cylinder phases in block copolymer thin films remains a major challenge. In this work, via a coarse-grained molecular dynamics simulation study, we report a solvent evaporation strategy starting from a mixed solution of A-b-B-type diblock copolymers (DBCs) and single-chain nanoparticles (SCNPs) with the same composition, which is capable of spontaneously generating PODs in drying DBC films induced by the interface segregation of SCNPs. The latter occurs at both the free surface and substrate and, consequently, neutralizes the interface selectivity of distinct blocks in DBCs, leading to spontaneous formation of PODs at both interfaces. The interface segregation of SCNPs is related to the weak solvophilicity of the internal cross-linker units. A mean-field theory calculation demonstrates that the increase in the chemical potential of SCNPs in the bulk region drives their interface segregation along with solvent evaporation. We believe that such a strategy can be useful in regulating the PODs of DBC films in practical applications. [ABSTRACT FROM AUTHOR]

Thermocapillary convection was investigated in a metallic system of pure Ni, at the nanoscale, by molecular dynamics. The system interface was irradiated by a heat flux, mimicking a focused laser source. The melt pool was submitted to a large temperature gradient that modified the surface tension along the interface. In liquid metal, because surface tension typically decreases with increasing temperature, the result is a gradient of surface tension along the free surface. The liquid metal, therefore, started to flow in the direction of high surface tension. Two counter-rotating convection cells developed, characteristic of those observed in welding and other material processing. A systematic estimation of relevant parameters in hydrodynamics allowed us to interpret the results in terms of Prandtl, Marangoni, and Péclet numbers. This study demonstrates the influence of laser power and system size on pool shape and flow characteristics. [ABSTRACT FROM AUTHOR]

This study uses the triple-phase lag model to investigate how higher-order fractional order and memory-dependent derivatives affect reflection at the free surface of an orthotropic piezo-thermoelastic medium. The performance of both kinds of derivatives is studied using the normal mode analysis technique. Four different types of coupled reflected plane waves are identified and explore the impact of various parameters, fractional order parameter, kernel function, the higher-order time differential fractional, and memory-dependent heat conduction parameters on energy distribution with respect to the angle of incidence. The results are presented graphically, providing numerical data for reflected waves, amplitude, and energy ratios. [ABSTRACT FROM AUTHOR]

This study investigated the chemical properties of peat microparticles modified asphalt (Pt.M.A.). The originality of the study resides in the examination of the chemical characteristics of peat microparticles (Pt.) modified asphalt (Pt. M.A.) utilising FTIR, SEM, SFE, and XRD methodologies. This encompasses Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), surface free energy (SFE), and X-ray diffraction (XRD). Initially, FTIR examined the functional groups of both unaltered and altered asphalt binders. The SEM images reveal improved compatibility, showcasing superior diffusion of the modifier across the asphalt. A further critical factor is that improved adhesion properties, according to the SFE study, indicate that modified binders generally offer more SFE compared to unmodified binders. The XRD measurements revealed a semi-crystalline structure in the Pt. modifier and an amorphous structure in the basal asphalt binder. The integration of Pt. into the asphalt cement resulted in modifications to the phases of both constituents, culminating in the emergence of a new semi-crystalline phase inside the modified asphalt binder. These data suggest that peat microparticles (Pt.) can improve the efficacy of asphalt binders by enhancing compatibility, adhesion, and resistance to ageing. [ABSTRACT FROM AUTHOR]

Recent breakthroughs in protein structure prediction have enhanced the precision and speed at which protein configurations can be determined. Additionally, molecular dynamics (MD) simulations serve as a crucial tool for capturing the conformational space of proteins, providing valuable insights into their structural fluctuations. However, the scope of MD simulations is often limited by the accessible timescales and the computational resources available, posing challenges to comprehensively exploring protein behaviors. Recently emerging approaches have focused on expanding the capability of AlphaFold2 (AF2) to predict conformational substates of protein. Here, we benchmark the performance of various workflows that have adapted AF2 for ensemble prediction and compare the obtained structures with ensembles obtained from MD simulations and NMR. We provide an overview of the levels of performance and accessible timescales that can currently be achieved with machine learning (ML) based ensemble generation. Significant minima of the free energy surfaces remain undetected. [Display omitted] • Ensemble prediction quality depends on training input to AlphaFold 2 (AF2) • MSA subsampling predicts ensembles but may miss key protein conformations • Current ensembles cannot reliably determine free energy, conformations, or properties • ⁠Ensemble data is crucial to improve conformational model accuracy Riccabona et al. underscore the importance of accurate structural data in predicting protein structural ensembles. They note that although rapid methods like MSA subsampling can generate ensembles, they often overlook functionally significant conformations, thereby missing crucial kinetic and thermodynamic insights. [ABSTRACT FROM AUTHOR]

In this study, cryogenic‐temperature formal machining technique was used to process solution‐treated aluminum 7075 alloys, the mechanical properties, morphology, and microstructure of machined surface and produced chips are investigated. Results show machining temperature has a huge influence on chip and machined surface morphology, cryogenic‐temperature machining chips and machined surfaces possess better surface integrity, chips are continuous and smoother, and machined surfaces are flatter. In contrast, room‐temperature formal machining chips exhibit serrated cracks on their free surface and the machined surface produces more serious scaly spines phenomenon. Both cryogenic‐temperature and room‐temperature samples experience severe deformation, cryogenic‐temperature machining alumium 7075 alloys max microhardness has enhanced from 98 HV 0.1 to 174 HV 0.1, and cryogenic‐temperature samples’ microhardness is higher than corresponding room‐temperature samples’ microhardness among all machining parameters. Cryogenic‐temperature can effectively suppress dynamic recovery thus chips could store more dislocations and then possess smaller ultrafine‐grained structures, accounting for higher microhardness. Besides cryogenic‐temperature inhibits precipitation of solute cluster and second phase particles and plays a lubrication effect at tool‐chip interface, thus cryogenic‐temperature machining aluminum 7075 alloys could obtain superior machined surface quality/chip morphology to improve processability. (*: Equal contributi) [ABSTRACT FROM AUTHOR]

Wood–plastic composites (WPCs) combine the properties of plastics and lignocellulosic fillers. A particular limitation in their use is usually a hydrophobic, poorly wettable surface. The surface properties of materials can be modified using ion implantation. The research involved using composites based on polyethylene (PE) filled with sawdust or bark (40%, 50%, and 60%). Their surfaces were modified by argon ion implantation in three fluencies (1 × 1015, 1 × 1016, and 1 × 1017 cm−2) at an accelerating voltage of 60 kV. Changes in the wettability, surface energy, and surface colour of the WPCs were analysed. It was shown that argon ion implantation affects the distinct colour change in the WPC surface. The nature of the colour changes depends on the filler used. Implantation also affects the colour balance between the individual variants. Implantation of the WPC surface with argon ions resulted in a decrease in the wetting angle. In most of the variants tested, the most significant effect on the wetting angle changes was the ion fluence of 1 × 1017 cm−2. Implantation of the WPC surface also increased the surface free energy of the composites. The highest surface free energy values were also recorded for the argon ion fluence of 1 × 1017 cm−2. [ABSTRACT FROM AUTHOR]

The response of partially saturated granular cargoes during maritime transportation has resulted in the capsize and sinking of 27 bulk carriers at sea and the loss over 90 seafarers' lives in the last decade. The partially saturated granular material response to energy imparted during cargo loading, ship engine vibrations and vessel rolling motions from sea states causes a change in state of the granular cargo, which can lead to vessel instability and ultimately capsize. However, the mechanisms driving the response of partially saturated granular cargos within a bulk carrier hold are not well understood. This paper presents results from an experimental study of rolling table centrifuge model tests on a partially saturated silica sand to contribute to improved understanding of the response of granular cargoes during maritime transport. Observed settlement, pore pressure, moisture content and density changes during and/or following a sequence of large amplitude rolling motions are presented. The results indicate that for the conditions considered, a progressive upwards migration of pore water during rolling led to creation of a free surface of water above the granular sample that was left in a denser, lower moisture content sample compared to its initial state. Sloshing of free water on top of even a competent cargo during rolling motions of the ship can contribute to loss of ship stability and ultimately capsize. [ABSTRACT FROM AUTHOR]

Rock burst prevention is a critical concern in deep rock engineering. Combining laboratory tests and numerical simulations, this work investigates the cutting-seam method and its mechanism for preventing strain rock bursts. In the laboratory test, the true triaxial loading system is used to simulate rock strain bursts. The test results show that the cutting-seam samples better preserve their integrity compared to the sample without the measure. The cutting seam effectively halts the development of penetrating cracks on the free face. After the rock burst, the number of fragments from the cutting-seam samples significantly reduces compared to the intact sample. The debris characteristic analysis shows a better fractal characteristic in the fragment size-number than the fragment size-mass, with the fractal dimension decreasing from the intact sample to the single-seam and further to the double-seam sample. Acoustic emission results demonstrate that the cutting seam reduces the stored strain energy and cumulative damage in the rock sample during the loading, and the double-seam effect is better than the single-seam case. Based on the laboratory tests, discrete element simulations are conducted to reveal that the position, depth, and spacing of the cutting seam influence its effectiveness in preventing rock bursts. The influence mechanism and the parameter selection are also discussed. Finally, simulations applied to an engineering project verify that the cutting-seam method alters the surrounding stress distribution of the tunnel, shifting stress concentration zones deeper and effectively reducing strain energy density near the seams. These findings are expected to enhance the understanding of the cutting-seam approach and provide theoretical support for its practical application. Highlights: A cutting-seam approach is proposed and tested to prevent the strain rock burst. The cutting seam physically halts the penetrating cracks and minimizes damage to the free surface. Different cutting-seam parameters and their influences are discussed through laboratory and numerical tests. The cutting-seam method shifts the stress concentration area deeper and reduces the strain energy density nearby. [ABSTRACT FROM AUTHOR]

This is the sequel of the recent work Du et al. (Commun Math Phys 400:2137–2179, 2023) on axially symmetric gravity water waves with general vorticities, which has investigated the singular wave profile of the free boundary near the degenerate points. In this companion paper, we are interested in the regularity of the free surface of the water wave near the non-degenerate points. Precisely, we showed that the free boundary is C 1 , γ smooth for some γ ∈ (0 , 1) near all non-degenerate points. The problem is intrinsically intertwined with the regularity theory of the semilinear Bernoulli-type free boundary problem. Our approach is closely related to the monotonicity formula developed by Weiss in his celebrated work Weiss (J Geom Anal 9:317–326, 1999), and to a partial boundary Harnack inequality for the one-phase free boundary problem, which is due to De Silva (Interfaces Free Bound 13:223–238, 2011). Mathematically, we associate the existence of viscosity solutions with the Weiss boundary-adjusted energy. Compared to the classical approach of Caffarelli (Ann Sc Norm Super Pisa Cl Sci 15:583–602, 1988), we provide an alternative proof of the existence of viscosity solutions for a large class of semilinear free boundary problems. [ABSTRACT FROM AUTHOR]

Based on the elastic wave equation, a pseudoelastic pure P‐mode wave equation has been recently derived by projecting the wavefield along the wavefront normal direction. This pseudoelastic pure P‐mode wave equation offers an accurate simulation of P‐wave fields with accurate elastic phase and amplitude characteristics. Moreover, considering no S‐waves are involved, it is computationally more efficient than the elastic wave equation, making it an excellent choice as a forward simulation engine for P‐wave exploration. Here, we propose a new pseudoelastic pure P‐mode wave equation and apply the stress image method to it to implement the free surface boundary condition. The new pseudoelastic wave equation offers significantly improved computational efficiency compared to the previous pseudoelastic wave equation. Additionally, the wavefields simulated by this new pseudoelastic wave equation exhibit clear physical interpretations. We evaluate the accuracy of the new wave equation in simulating elastic P‐waves by employing a model with high‐velocity contrasts. We find that this new equation, which purely admits P‐waves, though having exact amplitude and phase behaviour as the elastic waves for transmission components, the amplitudes slightly suffer in the scattering scenario. The difference in amplitude between the elastic and our pseudoelastic increases as the contrast in velocity at the interface (interlayer velocity ratio) increases, especially the S‐wave velocities. This has negative implications on scattering from the free surface boundary condition or the sea bottom interface, especially if the shear wave velocity below the surface or the sea bottom is high. However, in cases where, like for land data in the Middle East, the transition to a free surface is smoother, the accuracy of the pseudoelastic equation is high. In all cases, regardless of the interlayer velocity ratio, the accuracy of the pseudoelastic wave equation in simulating the elastic case, for scattered waves, exceeds that of the acoustic wave equation in phase and amplitude. [ABSTRACT FROM AUTHOR]

The water stability of asphalt pavements has been a focus of attention in coastal municipal areas. This work thoroughly examined the adhesion and stripping properties of the asphalt–aggregate system under salt solution freeze–thaw cycle conditions. The investigation was conducted utilizing the differential capillary rise test, surface free energy (SFE) theory, and modified water boiling test. The experimental findings suggest that the surface tension of asphalt increases in a linear manner as the temperature exceeds 100°C. The asphalt surface layer experiences irreversible fatigue degradation after completing five freeze–thaw cycles, resulting in a complete breakdown of adhesion capabilities. During the third freeze–thaw cycle, the proportion of asphalt binder that was stripped off the slide rose by 83% due to the NaCl solubility surpassing 21%. Upon reaching seven freeze–thaw cycles, the asphalt's stripping area ratio on the slide increased by approximately 50%. The correlation study indicates that the adhesion of asphalt to the surface of the slide cannot be explained by the work of adhesion. These findings offer valuable insights for future research in this area. [ABSTRACT FROM AUTHOR]

In the context of actual surface wave conditions, the wave field is represented as a set of complex fluctuations that randomly change in both time and space, commonly known as "random waves." These random waves can be expressed mathematically as a combination of multiple monochromatic waves, each having unique phases, directions, and amplitudes. Frequency-domain phase-resolving wave models have been shown to be robust predictors of random wave propagation provided the dispersive characteristics are valid for the range of water depths considered. Recently, a new dispersive nonlinear mild-slope equation model was developed by establishing a closer correspondence between the scaling of nonlinearity, horizontal depth variation, and modulation scale during the derivation process. In this work, this new model is augmented with a wave-breaking dissipation model using frequency-squared dissipation weighting over the wave spectrum. The new model and previous models are compared with laboratory data for accuracy in modeling the evolution of the random wave spectrum. Overall, the new model demonstrates improved agreement with results compared with the previously derived models. The additional nonlinear terms of the model, indicating the interaction effects between amplitude and amplitude change, correct the overprediction of wave spectral energy from prior models, especially at the lower frequencies of the shallowest gauges. Furthermore, the predictions of free surface elevation by the newly derived model are in excellent agreement with the observations at the shallowest gauge, primarily due to the alleviation of phase mismatch caused by the additional terms. Lastly, we provide the nonlinear modification to linear wavenumber on the basis of the additional nonlinearity. [ABSTRACT FROM AUTHOR]

An airlift pump is a vertical tube that utilizes the buoyant effects of a gas to lift a liquid. Unlike a standard mechanical pump, the liquid flow rate through the airlift pump is not directly controlled; rather, it depends on the supplied gas flow rate, the tube length and diameter, and the relative height of the liquid supply free surface (submergence ratio). The present study uses the commercial CFD code ANSYS CFX to model the isothermal, 3D, transient flow in an airlift pump using water and air. The model applies pressure boundary conditions at both ends of the tube and specifies the mass flow rate of air through multiple openings in the side of the tube. The bottom of the tube is an inlet of water only and the outlet is a two-phase flow opening. A time-dependent, homogeneous, VOF two-phase RANS CFD modelling approach is used with the air treated as an ideal gas. This work found that a complete 3D domain was necessary for consistent prediction of the airlift performance and physically realistic two-phase flow structures. Statistical analysis of the two-phase flow structures was applied to characterize airlift pump instability and better understand the physics of the airlift pump. [ABSTRACT FROM AUTHOR]

Compared to traditional invasive techniques for wound closure, photocrosslinkable surgical adhesives with antibacterial properties offer significant advantages. These include ease of application, a controllable and efficient curing reaction, reduced risk of pain and infection, and effective leakage prevention. This study introduces a novel soybean oil-based nonisocyanate polyurethane prepolymer for use in such adhesives. The prepolymer, a hydroxyurethane functionalized with methacrylate and quaternary ammonium groups (QAs), was characterized through spectroscopic methods. The resulting UV-curable bioadhesives, synthesized via thiol-ene-methacrylate click-photopolymerization, incorporated limonene as a reactive diluent, a tetra-functional thiol crosslinker, and a photoinitiator. Elemental analysis confirmed the uniform distribution of QAs and sulfur atoms, indicating a homogeneous network structure, corroborated by high gel content values in both organic (84–92%) and aqueous media (91–99%), and a consistent tan δ peak as per DMTA. The optimized adhesives exhibited strong adhesion (up to 377 kPa) to gelatin sheets—a tissue-analogous substrate—and displayed suitable surface free energy (45–52 mN/m) as determined by contact angle measurements, suggesting favorable thermodynamic adhesion to skin. Additionally, the adhesives showed satisfactory cytocompatibility with L-929 fibroblast cells and antimicrobial efficacy against two gram-positive and gram-negative bacterial strains, indicating promising biological activity. [ABSTRACT FROM AUTHOR]

The phenomenon of liquid sloshing inside partially filled tank trucks adversely affects the stability of the tank trucks. In order to mitigate the negative effects of liquid sloshing inside the tank, this study proposes several baffle configurations and investigates their anti-slosh effect on liquid sloshing. First, a numerical model of liquid sloshing is established. Then, the effectiveness of the numerical model is validated by comparing the results of free surface deformation, wall pressure, and sloshing frequency obtained from simulations and experiments under identical conditions. During the research process, it was found that the air pressure formed in locally sealed spaces within the tank also plays a positive role in suppressing liquid sloshing. The research results indicate that, under low fill volumes, baffles fixed at the bottom of the tank are more effective in suppressing liquid sloshing inside the tank, while under high fill volumes, baffles fixed at the top of the tank are more effective. Considering the tank's airtightness, the air pressure formed in locally sealed spaces within the tank plays an important role in suppressing liquid sloshing when baffles are fixed at the top of the tank and the fill volume is high. [ABSTRACT FROM AUTHOR]

A numerical model is presented for solving the dam–reservoir interaction (DRI) problem in the time domain. The primary aim of this paper is to introduce a coupling method that could be simply implemented in a monolithic DRI model, yields a symmetrical system of equations, and maintains accuracy comparable to existing studies. The finite element method is employed to solve the equation of motion for the structure, and the finite volume method is for the Navier–Stokes equations in the fluid domain. These two solvers are coupled using an innovative approach to generate a pressure-based symmetric system of equations, which is resolved implicitly. Moreover, unlike most previous DRI studies, free surface waves are considered in the modeling procedure, and their effects are investigated. Comparison of the results with benchmark test cases from the literature demonstrates that the proposed numerical method is both straightforward and precise. [ABSTRACT FROM AUTHOR]

Keywords: Navier-Stokes equations; resolvent; free surface; solution formula; Lp estimates.GraphBy Yongting Huang and Tao LuoReported by Author; Author [Extracted from the article]

Deriving from the motion of a three-dimensional compressible viscous heat-conducting fluid in an infinite layer bounded above by a free surface, the paper is concerned with the asymptotic behavior of solutions to the linearized compressible Navier-Stokes equations in a strip domain. With the help of the explicit solution formula for the corresponding resolvent problem we have achieved, the time-decay estimates of solutions to this problem in $ L^p $ spaces, $ 2\le p<\infty $, are well established. Moreover, since we are interested in the linearized dynamic boundary condition of the surface wave problem, some exponential decay properties of the solutions are revealed. Our result is crucial and indispensable for developing the $ L^p $ theory for the free boundary problem of the full compressible Navier-Stokes equations. [ABSTRACT FROM AUTHOR]

Concepts and evolution of multi-scale modelling from the perspective of wave–structure interaction have been discussed. In this regard, both domain and functional decomposition approaches have come into being. In domain decomposition, the computational domain is spatially segregated to handle the far-field using potential flow models and the near field using Navier–Stokes equations. In functional decomposition, the velocity field is separated into irrotational and rotational parts to facilitate identification of the free surface. These two approaches have been implemented alongside partitioned or monolithic schemes for modelling the structure. The applicability of multi-scale modelling approaches has been established using both mesh-based and meshless schemes. Owing to said diversity in numerical techniques, massively collaborative research has emerged, wherein comparative numerical studies are being carried out to identify shortcomings of developed codes and establish best-practices in numerical modelling. Machine learning is also being applied to handle large-scale ocean engineering problems. This paper reports on the past, present and future research consolidating the contributions made over the past 20 years. Some of these past as well as future research contributions have and shall be actualized through funding from the Newton International Fellowship as the next generation of researchers inherits the present-day expertise in multi-scale modelling. This article is part of the theme issue 'Celebrating the 15th anniversary of the Royal Society Newton International Fellowship'. [ABSTRACT FROM AUTHOR]

Recently metal–organic frameworks (MOFs) have been demonstrated as potential precursors for obtaining single atom catalysts (SACs). Although SACs are attracting significant scientific attention due to their exceptional catalytic properties, the synthesis of SACs is still challenging due to their high surface free energy and this limits the growth of SACs. However, recent scientific research indicates that MOFs, due to their interesting structural feature, tunable pore size, high porosity, and exceptional thermal and chemical stability, can be an ideal candidate for the development of SACs. Current environmental crisis highly demands development of efficient photocatalysts for sustainable energy conversions such as photocatalytic hydrogen evolution, photocatalytic carbon dioxide, oxygen reduction, and so forth. MOF‐based SACs are emerging as most potent photocatalyst for such energy conversion. This review summarizes the advances in the field of MOF‐based SAC systems for photocatalytic energy conversions referred to above, along with mechanistic aspects. The complementarity of MOFs and SACs in the principle of photocatalysis have been elucidated. This review also seeks to offer an insight into the challenges involved and the future prospects of MOF‐based SAsystems. [ABSTRACT FROM AUTHOR]

A new type of SiCf/TiC-Ti3SiC2 composite was prepared by the Spark Plasma Sintering (SPS) method in this work. The phase transformation and interface cracking of this composite under ion irradiation (single Xe, Xe + He, and Xe + He + H ions) and subsequent annealing were analyzed using transmission electron microscopy (TEM), mainly focusing on the interface regions. Xe ion irradiation resulted in the formation of high-density stacking faults in the TiC coatings and the complete amorphization of SiC fibers. The implanted H ions exacerbated interface coarsening. After annealing at 900 °C for 2 h, the interface in the Xe + He + H ion-irradiated samples was seriously damaged, resulting in the formation of large bubbles and cracks. This damage occurred because the H atoms reduced the surface free energy, thereby promoting the nucleation and growth of bubbles. Due to the absorption effect of the SiCf/TiC interface on defects, the SiC fiber areas near the interface recovered back to the initial nano-polycrystalline structure after annealing. [ABSTRACT FROM AUTHOR]

The atmospheric boundary layer is a crucial transitional region connecting the surface with the free atmosphere, playing a bridging role in land-sea-air interactions and the interactions between different atmospheric layers. This study utilizes rotary-wing UAVs, high-resolution lidar, and WRF simulation data to analyze the vertical distribution characteristics of temperature, humidity, wind speed, and wind direction boundary layer over the Mount Si'e region in 4–6 April 2024. The results indicate that the boundary layer temperature decreases with increasing altitude, reaching up to 18°C, while humidity decreases with height, dropping to as low as 35%. Daytime wind speeds range from 4 to 8 m/s, decreasing to 2 to 4 m/s at night. The boundary layer height can reach up to 900 m during the day and drops to 100–200 m at night, showing distinct diurnal variation characteristics. UAV observations are in good agreement with lidar and WRF simulation results, highlighting the application value of UAVs in high temporal and spatial resolution boundary layer studies. The study also reveals the significant impact of complex terrain on boundary layer characteristics, providing scientific insights into the dynamic and thermal processes of the boundary layer and offering reference value for improving regional weather forecasting and numerical simulations. [ABSTRACT FROM AUTHOR]

Using angle-resolved X-ray photoelectron spectroscopy, sum-frequency generation vibrational spectroscopy, contact angle measurements, and molecular dynamics simulations, we verify that the glass transition temperature (Tg) of polymer glass is lower near the free surface. However, the experimental Tg-gradients showed a linear variation with depth (z) from the free surface, while the simulated equilibrium Tg-gradients exhibited a double exponential z-dependence. In typical simulations, Tg is determined based on the relaxation time of the system reaching a prescribed threshold value at equilibrium. Conversely, the experiments determined Tg by observing the unfreezing of molecular mobility during heating from a kinetically arrested, nonequilibrium glassy state. To investigate the impact of nonequilibrium effects on the Tg-gradient, we reduced the thermal annealing time in simulations, allowing the system to fall out of equilibrium. We observe a decrease in the relaxation time and the emergence of a modified z-dependence consistent with a linear Tg-gradient near the free surface. We further validate the impact of nonequilibrium effects by studying the dependence of the Tg on the heating/cooling rate for polymer films of varying thickness (h). Our experimental results reveal significant variations in the Tg-heating/cooling rate dependence with h below the bulk Tg, which are also observed in simulation when the simulated system is not equilibrated. We explain our findings by the reduction in mass density within the inner region of the system under nonequilibrium conditions, as observed in simulation, and recent research indicating a decrease in the local Tg of a polymer when placed next to a softer material. [ABSTRACT FROM AUTHOR]

Studying liquid jet impacts on a liquid pool is crucial for various engineering and environmental applications. During jet impact, the free surface of the pool deforms and a cavity is generated. Simultaneously, the free surface of the cavity extends radially outward and forms a rim. Eventually the cavity collapses by means of gas inertia and surface tension. Our numerical investigation using an axisymmetric model in Basilisk C explores cavity collapse dynamics under different impact velocities and gas densities. We validate our model against theory and experiments across a previously unexplored parameter range. Our results show two distinct regimes in the cavity collapse mechanism. By considering forces pulling along the interface, we derive scaling arguments for the time of closure and maximum radius of the cavity, based on the Weber number. For jets with uniform constant velocity from tip to tail and $We \leqslant 150$ , the cavity closure is capillary-dominated and happens below the surface (deep seal). In contrast, for $We \geqslant 180$ the cavity closure happens above the surface (surface seal) and is dominated by the gas entrainment and the pressure gradient that it causes. Additionally, we monitor gas velocity and pressure throughout the impact process. This analysis reveals three critical moments of maximum gas velocity: before impact, at the instant of cavity collapse and during droplet ejection following cavity collapse. Our results provide information for understanding pollutant transport during droplet impacts on large bodies of water, and other engineering applications, like additive manufacturing, lithography and needle-free injections. [ABSTRACT FROM AUTHOR]

The situation of two ships maneuvering in the vicinity is not so rare, and the significant hydrodynamic interaction effect always poses a threat to navigation safety in these conditions. The assessment of the Distance at Closest Point of Approach (DCPA) is necessary for ship collision avoidance decision-making. In this study, an efficient ship maneuvering model for close-distance maneuvering is developed to predict DCPA rapidly, where the hydrodynamic interaction between ships is accounted for. The Maneuvering Modeling Group (MMG) standard model is used to predict ship motion, and the hydrodynamic interaction effect is estimated in real-time by a code based on the potential flow theory where the variation of free surface is neglected. The ship maneuvering model is validated by the comparison between simulation and experiment in turning and zig-zag maneuvering; furthermore, the validated maneuvering model is used to predict the trajectory under the ship hydrodynamic effect. The characteristic of ship maneuvering under the ship hydrodynamic interaction between two ships is described and illustrated, and the influence of the velocity and lateral distance on the ship trajectory is revealed. A sensitivity analysis of the maneuvering model is performed to determine whether the hydrodynamic interaction effect is necessary to be evaluated exactly for an accurate predicted trajectory and DCPA. The DCPA in different situations is calculated, which represents the ship collision risk. [ABSTRACT FROM AUTHOR]

Proper pressure drop conditions are essential in predicting hydrodynamic performance of perforated structures in the framework of a potential flow theory. In this study, we investigate water waves passing through a perforated plate with various pressure drop models to examine how pressure drop conditions affect the hydrodynamic performance of perforated structures. We derive the analytical solutions of waves across the perforated plate by adopting three commonly pressure drop conditions, including one linear pressure drop condition (LPDC), and two quadratic pressure drop conditions (QPDCs). A series of laboratory experiments are conducted to validate the present theoretical results. We compare the hydrodynamic performance between the experimental data and the theoretical solutions with the three different pressure drop models, typically for wave reflection coefficients, dynamic pressures, and velocity fields measured by the technique of particle image velocimetry in the experiments. It is found that the existing pressure drop models can predict well wave reflection coefficients, dynamic pressure, and velocity profiles at certain conditions. However, the linear wave solutions associated with LPDC or QPDCs generally underpredict the amplitude of particle velocity near the free surface on the perforated plate. This underestimation increases largely as the wave steepness increases. The LPDC performance relies much on the selection of empirical coefficients. For the QPDCs, the analytical models show deviated results from the experimental data for wave reflection coefficients when the wave steepness is relatively low. [ABSTRACT FROM AUTHOR]

When a cavitation bubble re-expands near the surface of a liquid, an axisymmetric crown forms around the jet that is initially produced. Controlling this crown is essential if the first jet is to be used in engineering applications such as laser-induced transfer (LIT). Herein, we introduce a second cavitation bubble to control the formation and growth of the crown. Numerical simulations were performed using the compressibleInterIsoFoam solver within the open-source platform OpenFOAM, incorporating a geometric volume-of-fluid approach for tracking interfaces. Detailed analysis showed that a reversal in curvature across the concave interface indicates the moment of crown formation, and this is induced by flow focusing during bubble contraction or momentum transfer from a second expansion. In the presence of the second bubble, the crown type can be classified as either enhanced or inhibited in comparison with a single-bubble scenario. The velocity of crown formation, v cf , is defined to describe the crown type, and a parametric study of crown types was conducted based on the dimensionless stand-off distances, γ 1 and γ 2 . The findings of this study offer new insights into the field of LIT. [ABSTRACT FROM AUTHOR]

This study addresses the horizontal and vertical dispersion of passive tracers in idealized wind-driven subtropical gyres. Synthetic particles within a closed basin are numerically advected to analyze their dispersion under different theoretical velocity fields. Horizontal dispersion simulations incorporate the classic wind-driven Stommel circulation along with (i) surface Ekman drift associated with the Stommel wind field and (ii) inertial effects due to particle size and buoyancy. Results reveal that the Ekman drift inhibits particle dispersion across the entire domain leading to tracer concentration in a quasi-stable distribution skewed toward the western side of the basin. Similar behavior is observed with inertial particles. The equilibrium state is quantified for different diffusivity values, particle sizes, and buoyancies. For vertical dispersion, simulations incorporate the three-dimensional Ekman velocity, which includes a negative vertical component, while ignoring inertial effects. Initially, surface particles accumulate around the gyre center while slowly sinking, but they disperse across the basin once they surpass the Ekman layer and are free from surface effects. Tracers sink more on the western side of the basin, regardless of horizontal diffusivity. On average, ignoring inertial effects, particles sink less with higher diffusivity and more with lower diffusivity, suggesting a potential for high horizontal distribution of sunken tracers in the ocean. [ABSTRACT FROM AUTHOR]

The study focused on the variations of slosh patterns in three-dimensional rectangular tanks under oblique translational excitations by using an in-house Navier–Stokes model. The model was validated against different slosh patterns and then used to explore how the slosh pattern changed with various excitation frequencies. The excitation frequencies were divided into two categories: multiples of the first-order and third-order natural frequencies. The influences of the excitation frequency, excitation angle, and base ratio on the slosh pattern were identified by examining the free surface displacements and the sloshing forces, as well as their correlations. It was found that excitation frequencies related to the third-order natural frequency resulted in similar slosh patterns with more complicated free surface shapes compared to those related to the first-order natural frequency. Excitation angles had little influence on non-resonant cases but could remarkably affect the local features of other wave patterns and correlated beating periods. The slosh pattern was generally not affected by various base ratios, but the local wave shapes and dominant orientations would change. [ABSTRACT FROM AUTHOR]

Fat, oil, and grease (FOG) floating particles in the sump of sewage pumping stations will accumulate together to form rigid layers, resulting in failure for pump device. To overcome this, the free surface vortex (FSV) technique has been considered and applied to transport floating particles toward the submerged suction pump inlet. This paper investigates the potential of vortices as a means of downward motion of FOG. The entrainment capacity of FSV is investigated by numerical simulations using a coupled level-set and volume-of-fluid method. Two coherent structures are decomposed by proper orthogonal decomposition: FSV represented by the first two orders with high energy content and spiral vortex bands represented by low energy and high order models. The extracted ridges of the finite-time Lyapunov exponent (FTLE) delineate different regions of the flow field and effectively capture the evolution of Lagrangian coherent structures. The floating particles in the sump are first caught by the dividing line formed by the FTLE ridges, mixed in the entrainment zone, and then merged into the vortex. The enstrophy production term dominates the development of vorticity. Subject to the influence of flow velocity gradients, both radial and tangential vortices undergo a transition into axial vortices. This transformation enhances the vortex's capacity to entrain particles within the vortex core area, leading to their rapid inward spiraling toward the vortex center and eventual expulsion due to the vortex's entrainment effect. [ABSTRACT FROM AUTHOR]

Wave nonlinearity and free surface effects are recognized as important factors for sediment transport under nonlinear waves. Existing studies primarily focus on oscillatory water tunnel (OWT) instead of real waves for sediment transport due to the challenges in constructing real-scale wave tank. In contrast to OWT, the wave tank performs both wave nonlinearity and free surface effect on sediment transport. A numerical wave-sediment tank is developed for strong nonlinear wave propagation over sediment bed with low computational cost. The nonlinear wave is generated by defining the inlet boundary condition and absorbed by using a damping function, and the classical volume of fluid method is used to handle the free surface. The numerical tank further considers particle wake vortex effect and modifications in relative velocity of high sediment concentration, and incorporates phase lag, mass conservation, acceleration effect, and asymmetric wave boundary layer into near-bed sediment conditions. Therefore, the numerical tank avoids complex calculations for near-bed hyper-concentrated sediment in comparison with a two-phase model, i.e., the calculation of particle collision, friction, and detection of mobile bed surface. The numerical tank reasonably agrees with large-scale wave flume experiments and a two-phase model including free surface wave, and successfully performs sediment transport induced by strong nonlinear (second-order Cnoidal) wave. Compared to the OWT, the extra onshore streaming caused by free surface wave significantly enhances onshore sediment transport. [ABSTRACT FROM AUTHOR]

The statistical characteristics of bubble plumes generated by inclined liquid jets remain inadequately understood, particularly regarding their spatial evolution. This study employs an optical fiber probe for sequential multi-point measurements to investigate the evolution of bubble plumes produced by shallow-angle inclined jets impacting both quiescent fluid and crossflow. Measurements of air volume fractions reveal that crossflow significantly attenuates the jet's penetration capability. Under both conditions, the bubble size distributions exhibit power-law behavior, with variations in the exponents observed at different spatial locations. In quiescent water, a power-law exponent of −2 is observed within the jet impact region, where the strong shear effect of the oblique jet introduces more large bubbles and extends their survival time. This exponent gradually decreases with increasing distance from the jet's influence. In the presence of crossflow, the bubble size spectrum closely resembles that observed under breaking waves. This similarity arises because the jet induces intense surface overturning and fragmentation, becoming the primary source of bubble entrainment. Multi-point measurements further indicate that bubble fragmentation dominates near the free surface, while bubble coalescence becomes more prevalent at greater depths. The results for the bubble velocity distribution indicate that, under both conditions, the distribution of high-speed bubbles follows a power law with an exponent of −6. However, the physical mechanisms driving this behavior remain unclear. [ABSTRACT FROM AUTHOR]

The effect of ring baffles on suppressing the three-dimensional (3D) resonant sloshing in an upright cylindrical container is experimentally investigated. The main objectives of this work are to examine the effectiveness of various baffle configurations, to establish the stability boundaries of the stable steady-state waves in the unbaffled and baffled containers, to provide accurate experimental data for the verification of the analytical and numerical models, and to prompt future investigations. For this purpose, hundreds of sloshing experiments are conducted in a cylindrical container with or without a ring baffle. An analytical potential-flow solution and an asymptotic multimodal method are used to elucidate the experimental results. It is found that the vertical location of the ring baffle has small influence on the fundamental natural frequency of the system; however, it has a significant influence on the viscous damping and the damping rate increases gradually with the ascension of the baffle. When the distance between the baffle and the free liquid surface is sufficiently large, the system exhibits three types of resonant wave patterns, namely stable planar, stable swirling, and irregular chaotic. These wave patterns are qualitatively and quantitatively similar to those in the unbaffled container. When the baffle is near the free liquid surface, neither the chaotic waves nor the swirling waves take place, but a new wave pattern with the characteristic of multiple wave crests is observed. Probably, this is the first time that the 3D resonant sloshing in the baffled cylindrical container has been systematically investigated. [ABSTRACT FROM AUTHOR]

The coupled problem of liquid sloshing in a tank with a membrane cover and elastic side walls is investigated. The velocity potential theory is used for the flow and the linear elastic theory for the cover and side walls. For the former, the vertical mode expansion is used, in which all the roots of the dispersion relationship are first found. The expansion automatically satisfies the governing equation, the tank bottom, and the tank cover conditions. The deflections of the side walls are expanded into a cosine series together with a four term polynomial, which is vital for the procedure to succeed. These expansions are then matched through the dynamic and kinematic equations of the plates, and the problem is completed by imposing the edge conditions of the plate and membrane. Through the combined matrix equation, the natural frequencies of the system are obtained. In addition, the nature of the dispersion relationship of the membrane is analyzed. Explicit solutions are obtained for some special cases, and the link with the free surface sloshing is established. Extensive numerical results are provided, and their physics is analyzed. [ABSTRACT FROM AUTHOR]

The dynamics of liquid droplets surfing over the surfactant-infested free surface of another liquid have been explored experimentally. We analyze the motion of oil droplets that has been initiated through the creation of a surface tension gradient resulting from the deposition of a drop of surfactant at the water surface contained in the petri dish. The experiments reveal that the location of surfactant deposition with respect to the droplet position influences its motion. Due to the presence of a surface tension gradient, the footprint area of the droplet reduces and its shape changes. We have studied the temporal variation in the velocity (| v x |) of the droplets in relation to their proximity to a wall. Based on the evolution of droplet shape and change in droplet velocity, the drop dynamics can be experimentally divided into four distinct zones. Results indicate that in zone-1, | v x | grows with t as | v x | ≈ t n , where n is between 0.8 and 1.0. The scaling argument shows that in this zone, the surface tension force dominates the drag force, and thereby, | v x | of the droplets increases linearly with t expressed as | v x | ∝ t. The experimental investigation and the scaling law exhibit a reasonable agreement. In zone-2, | v x | remains more or less constant, as it is postulated that the surface tension force balances the drag force. In zone-3, a decrease in surface tension force results in a deceleration of the droplets. In zone-4, the deceleration becomes more prominent as the droplet approaches the petri dish wall. [ABSTRACT FROM AUTHOR]

In this work, the influence of evaporative flux over the atomization driven by surface acoustic waves (SAWs) of a Newtonian water drop is studied. The drop is placed on a heated substrate at constant temperature, higher than the saturation temperature at a given vapor pressure. In this manner, an interfacial temperature distribution arises along the drop free surface in terms evaporative mass flux and vapor recoil, which repercussion over aerosol size is studied by determining the asymptotic evolution equation governing the acoustically driven free surface. At such scenario, the connection between surface tension and temperature is also considered; thus, thermocapillary flow is incorporated into our drop model, described in terms of fundamental parameters, like the evaporation number, Marangoni number, and acoustic capillary number. Numerical solution of the evolution equation led us to obtain a simplified representation of the drop interfacial deformation mechanism, capable of predicting atomization and portraying the influence of evaporation over atomization. Subsequent analysis shows that the incorporation of evaporation at SAW atomization traduces in normal stresses counteracting the acoustic and thermocapillary effect, leading to the development of smaller drop aspect ratios with respect to the no-evaporative case. Being aware that the aerosol size is deeply related to the aspect ratio, we propose an analytical expression to estimate aerosol diameter under evaporative conditions. The results show that aspect ratio reduction leads to a decrement on aerosol size, up to two orders of magnitude, with respect to the no-evaporative case. Our study is a first approach providing insight about the importance of evaporation on aerosol regulation at SAW atomization. [ABSTRACT FROM AUTHOR]

Recent observations show that certain rupture phase can propagate backward relative to the earlier one during a single earthquake event. Such back‐propagating rupture (BPR) was not well considered by the conventional earthquake source studies and remains a mystery to the seismological community. Here we present a comprehensive analysis of BPR, by combining theoretical considerations, numerical simulations, and observational evidences. First, we argue that BPR in terms of back‐propagating stress wave is an intrinsic feature during dynamic ruptures; however, its signature can be easily masked by the destructive interference behind the primary rupture front. Then, we propose an idea that perturbation to an otherwise smooth rupture process may make some phases of BPR observable. We test and verify this idea by numerically simulating rupture propagation under a variety of perturbations, including a sudden change of stress, bulk or interfacial property and fault geometry along rupture propagation path. We further cross‐validate the numerical results by available observations from laboratory and natural earthquakes, and confirm that rupture "reflection" at free surface, rupture coalescence and breakage of prominent asperity are very efficient for exciting observable BPR. Based on the simulated and observed results, we classify BPR into two general types: interface wave and high‐order re‐rupture, depending on the stress recovery and drop before and after the arrival of BPR, respectively. Our work clarifies the nature and excitation of BPR, and can help improve the understanding of earthquake physics, the inference of fault property distribution and evolution, and the assessment of earthquake hazard. Plain Language Summary: Under the traditional view on earthquakes, rupture is typically considered to propagate away from where it starts, a process called forward propagation. However, recent studies show that sometimes rupture can reverse its propagation direction relative to the earlier one, which is referred to as back‐propagating rupture (BPR). The lack of a comprehensive understanding of BPR motivates us to explore why and how BPR could occur, by combining theoretical analyses, computer simulations, and experimental or natural observations. Our theoretical analyses suggest that BPR in terms of back‐propagating stress wave should almost always exist during dynamic ruptures, but can also be masked by the canceling effect of interfering waves. Nonetheless, introducing perturbations during a relatively smooth rupture process may highlight certain phases of BPR. We verify the above idea by computer simulations and available observations, showing that perturbed rupture propagation, for example, by the encountering of free surface, another rupture, and fault asperity, indeed can excite observable BPR. We further classify BPR into interface wave and high‐order re‐rupture, when there is a negligible and finite offset to the baseline of shear stress, respectively. Our work provides new insights into earthquake source process and can help improve earthquake hazard assessment. Key Points: Back‐propagating rupture (BPR) (as stress wave) is an intrinsic feature during dynamic ruptures but can be masked by destructive interferenceObservable BPR can be excited by introducing a variety of perturbations to an otherwise smooth rupture processBPR represents interface wave or high‐order re‐rupture, and can help infer the evolution behind the primary rupture [ABSTRACT FROM AUTHOR]

The free‐surface lattice Boltzmann method uses a volume of fluid approach to simulate immiscible two‐fluid flow problems. It divides the simulation domain into three distinct phases—gas, fluid, and interface—where computation within the gas phase is disregarded. The interface delineates a one‐cell‐thick layer between the first two phases, validated physically for implementation in the HPC C++ multiphysics framework waLBerla but lacking an exhaustive performance analysis. This paper aims to shed light on node‐level performance on different architectures, employing continuous benchmarking, showing and analyzing weak scaling results on a modern HPC cluster, the Fritz supercomputer, and reporting energy consumption for the current implementation. [ABSTRACT FROM AUTHOR]

This paper deals with propagation of Rayleigh-type waves in nonlocal inhomogeneous transversely isotropic half-space. From the characteristic equation of wave for the nonlocal inhomogeneous transversely isotropic medium, the existence of the number of surface waves depends on the inhomogeneity of the medium through the number of solutions satisfying the damping condition of the characteristic equation discussed. It has also been concluded that there exist cut-off frequency and escape frequency for the wave propagating in size-dependent materials based on the nonlocal theory. Dispersion equation for the propagation of Rayleigh-type surface waves at the free surface has been derived. Based on the obtained dispersion equation, the effects of the inhomogeneity of material and nonlocality parameter on the Rayleigh wave propagation are considered through some numerical examples. [ABSTRACT FROM AUTHOR]

The mobility of the Wigner solid on the free surface of superfluid 3 He is determined by the momentum transfer from the scattered 3 He quasiparticles at the free surface. The scattering process of the quasiparticles is classified into the normal reflection and the Andreev retroreflection. Since the quasiparticles nearly conserve the momentum in the process of the Andreev retroreflection at the free surface, the Andreev-reflected quasiparticles do not produce a resistive force to the Wigner solid. In this report, we have analytically calculated the contribution of the Andreev retroreflection to the mobility of the Wigner solid on superfluid 3 He-B by employing a realistic model order parameter with the free surface. The Andreev retroreflection is absent for quasiparticles with energies above the bulk energy gap under the model order parameter. Then, the Andreev retroreflection does not contribute to a rise in the mobility of the Wigner solid on the superfluid 3 He-B. The present model calculation is in good agreement with the previous experimental observation. We have also discussed the Andreev retroreflection under a self-consistently calculated order parameter. [ABSTRACT FROM AUTHOR]

This study aims to evaluate the adsorptive, adhesive, and wetting energetic properties of five commercially available cleansers in contact with model dental polymer (PMMA). It was assumed that the selected parameters allow for determining the optimal concentration and place of key component accumulation for antibacterial activity in the bulk liquid phase and prevention of oral plaque formation at the prosthetic material surface. The adsorptive (Gibbs' excesses ΓLV, critical micellar concentration) and thermal (entropy and enthalpy) surface characteristics originated from surface tension γLV(T) and γLV(C) dependences. The surface wetting properties were quantified upon the contact angle hysteresis formalism on the advancing ΘA, receding ΘR contact angles, and γLV as the input data, which yield a set of wettability parameters: 2D adsorptive film pressure, surface free energy with its dispersive and polar components, work of adhesion, and adhesional tension, considered as interfacial interaction indicators. In particular, molecular partitioning Kp and ΓLV are indicators of the efficiency of particular active substance accumulation in the volume phase, while γSV, a = ΓSL/ΓLV, and WA point to the degree of its accumulation at the immersed polymer surface. Finally, the liquid penetration coefficient PC and the Marangoni temperature gradient-driven liquid flow speed were estimated. [ABSTRACT FROM AUTHOR]

Scots pine (Pinus sylvestris L.) wood is one of the most popular timber export products. However, its low durability can reduce the potential and utilization of the wood. Chemical modification is one of the solutions to overcome this drawback. Chemical modification using non-biocide materials such as glycerol and citric acid was carried out to improve the inferior properties of wood. The study aimed to observe the microstructure and evaluate the surface characteristics of glycerol and citric acid-modified scots pine wood. Scots pine wood was modified using glycerol and citric acid with weight percent gain (WPG) values of 20% and 46%. Surface characteristics were measured, including surface roughness, surface free energy (SFE), wettability, and bonding quality. The results show that chemical modification using glycerol and citric acid resulted in the structure of the pine wood being more filled and denser. The modification could also reduce the roughness of the wood surface, resulting in decreased SFE value, increased contact angle, and decreased wettability on the wood surface. It might cause a decrease in the bonding quality because the wood did not have the strength to mechanically lock with the paint. Glycerol and citric acid modified-scots pine wood can be considered for exterior application. [ABSTRACT FROM AUTHOR]

In the past two decades or so, ambient noise tomography (ANT) has emerged as a powerful tool for investigating high-resolution crustal and upper-mantle structures. A crucial step in the ANT involves extracting phase velocities from cross-correlation functions (CCFs). However, obtaining precise phase velocities can be a formidable challenge, particularly when significant lateral velocity variations exist in shallow subsurface imaging that relies on short-period surface waves from ambient noise. To address this challenge, we propose an unwrapping correction method that enables the accurate extraction of short-period dispersion curves. Our method relies on the examination of the continuity of phase velocities extracted from CCFs between a common station and other neighbouring stations along a linear array. We demonstrate the effectiveness of our approach by applying our method to both synthetic and field data. Both applications suggest our unwrapping correction method can identify and correct unwrapping errors in phase velocity measurements, ensuring the extraction of accurate and reliable dispersion curves at short periods from ambient noise, which is essential for subsequent inversion for subsurface structures. [ABSTRACT FROM AUTHOR]

Observations of the seafloor Rayleigh ellipticity contribute to seismic imaging in the ocean. To extract such observables from the arbitrarily oriented ocean–bottom seismometer (OBS) data, we develop an orthogonal-regression-based approach to measure the waveform amplitude ratios of the unoriented horizontal and vertical components. The amplitude ratios are then used to calculate the Rayleigh ellipticity (and the sensor orientation angle). The robustness of our method is verified by applications to both the unoriented OBS data and the well oriented on-land seismic data. As we propose to calculate the Rayleigh ellipticity directly from the unoriented three-component data, the measurement process avoids the complexity arising from the surface wave non-great-circle effects and uncertainties of the OBS sensor orientation angles. Overall the Rayleigh ellipticity measurements from our method are systematically higher than those by conventional analysis and show less uncertainties. Our analyses suggest that the Rayleigh ellipticity curve (14–60 s), which could be retrieved from the raw broad-band OBS data, is effective to constrain the oceanic lithosphere structure, and the accurate measurement of Rayleigh ellipticity curve is important. The potential of seafloor Rayleigh ellipticity for seismic imaging in the ocean is evidenced by a case study of the Japan Basin, the Sea of Japan. Considering the insufficient station coverage in the ocean, the single-station measurement of seafloor Rayleigh ellipticity is of significance for OBS community. [ABSTRACT FROM AUTHOR]

Crystallization via nucleation can isolate active pharmaceutical ingredients from their crudes. While chemical engineering textbooks provide theoretical knowledge on crystallization and nucleation theories, they often fall short in providing provide practical insights on the nucleation mechanism. To bridge this gap, we introduced a virtual experiment on nucleation in second-year chemical engineering classrooms. The main goal is to educate students on crystallization procedures in research and process industries, teaching them how to analyse and manage collected data while integrating theoretical knowledge. This includes conveying the kind of information that can be obtained from a crystallisation process and instructing students on how to analyse and manage the data collected in the light of the theories learned. We devised an original chemical engineering problem on nucleation, derived directly from the raw data collected in the classroom from virtual experiments. This method differs from the conventional approach of solving standard textbook problems. The textbook problems, regrettably often lack crucial information on how nucleation rate or surface free energy are directly obtained from raw data. By the conclusion of the virtual experiment, students have acquired a comprehensive understanding encompassing both practical and theoretical aspects of crystallization, with a particular focus on nucleation. The methodologies elucidated in this study can be applied across a spectrum of chemical engineering modules, including process engineering, unit operations in chemical engineering, mass transfer, and can even be integrated into specialized courses dedicated to crystallization. • Problems were developed in classroom based on experimental data from virtual lab. • Virtual experiments on nucleation deployed in third year chemical engineering classrooms. • Example problems on crystal nucleation developed in collaboration with students in the classroom. • Students solve the example problems developed by them in the classroom. [ABSTRACT FROM AUTHOR]